Female reproductive system. Female sex hormones. Steroids hormones. Synthesized from cholesterol precursor. Converted from one to the other in the appropriate times which have the required enzymes. Produced in the ovaries mainly but the adrenal cortex produce minimal amounts.
It bound to carrier protein. Then, it attached to specific receptors on the cell membrane. They enter cell and become bound to a cytoplasm protein receptor and form a steroid protein complex which attached to the nucleus and stimulate the RNA synthesis which stimulate protein synthesis and regulate cell functions.
Cutaneous gland development – axillary and pubic apocrine glands begin to function at the same time that pubic and axillary hair appear which cause change in body odour. The sebaceous gland secretion becomes thicker which predisposes to blockage or acne, sweat glands of the body become more active.
Cyclic oestrogen secretion results in regulation of gonadotrophic hormone where:
In mid-cycle, high level of oestrogen induces LH surge (positive feedback) also progesterone feedback at the mid-cycle to enhance LH surge.
Adverse effects of administered oestrogen (oral contraceptive).
In the breast development, it exerts its effect on the alveolar tissue and lobules in growth in size during adolescence and pregnancy.
Each month a few primordial follicles start to grow in response to the rising level of pituitary FSH. Most of the follicles will undergo atresia and only one “leading” follicle will continue development and be able to respond to LH and progress to ovulation. The functional and morphological changes which occur in the ovaries and ovarian follicles during menstrual cycle divided into 3 stages:
The theca cells differentiate into a well vascularized theca interna and less vacularized theca externa. The theca cells respond to LH by synthesizing androgens which pass the granulosa cells to be transformed into progesterone.
The uterine cycle – the myometrial and endometrial tissues respond to the ovarian hormones
Within 48 hours after the menstruation, there is change in the epithelial layer from the remnants of glands in the basal part of the endometrium and it responds to ovarian hormones. There are 3 phase; proliferative phase, secretory phase and menstrual phase
a) The proliferative phase – it starts from the end of menstruation and lasts until the time of ovulation. The glands appear tubular, lined by low columnar cells, they become large and convoluted. The stromal cells ↑ in number and become more oedematous. The blood supply also grows. The basal layer supplied by straight arteries and the superfacial part is supplied by spiral arteries (endometrium grows from 0.5mm to 5mm). Oestrogen is the dominant hormone and it corresponds to the follicular phase of the ovary.
b) The secretory phase – from the time of ovulation until menstruation, progesterone is the dominant hormone and it corresponds to the luteal phase of the ovary, under the influence of progesterone endometrial growth ceases and there is functional changes to prepare the tissue for the embryo. The glands start to secrete and discharge their contents into the lumen of the glands (which consists of glycogen, sugars, acids, mucus and enzymes such as alkaline phosphatase). The arteries become more prominent and more coiled and continue to grow while the endometrium height remains static. In the late luteal phase changes depends whether implantation has taken place or not
Implantation – if pregnancy occurs, the developing embryo secretes hCG which maintains the corpus luteum which continue to secrete oestrogen and progesterone. Changes in the endometrium occurs and involve the stromal cells which differentiate into 3 layers
c) Menstruation – interstitial haemorrhages due to breakdown of the superficial arteries and non viable tissues are extended into the uterine cavity and lead to menstrual flow. There is shedding of all the layers except the deep endometrial layer.